Custom exits for xsodata should be specified using their repository names. In your case "PAL::customerupdate" should refer to an object in the repository. So PAL should be a package that has a file name customerupdate.hdbprocedure. But for you it is not the case, PAL is the schema name. Please create the procedure in repository and refer this for the exit.
Alternatively, as a workaround, you can create a public synonym PAL::customerupdate.
create public synonym "PAL::customerupdate" for PAL."CustomerUpdate"
A side note:It is better to create a new discussion for questions unrelated to the original one.